On Tuesday 14 October 2008 03:52:35 Andy Walls wrote:
> Well, things are kinda of ugly, but I can at least get a few VBI
> buffers out of the CX23418 (and then it stops).
>
>
> To get reasonable looking raw VBI captures, for NTSC, I had to set
> the VBI buffer size to 26 lines * 1444 samples and tell the encoder
> to send 13 lines per field. (I guess the CX18-AV-Core is setup to
> send 13 lines per field). I commented out the "compression" done in
> the cx18 driver to get the unmolested, but still byte swapped,
> buffers.
>
> The CX23418 throws in a 12 byte sequence before the first VBI line,
> and again in the last 12 bytes of the last line of the frame. Here's
> a dump from a little utility I wrote to show where things get aligned
> when capturing with 'cat /dev/vbi >foo.vbi'.
>
> code 0x3fffffff found at 0 (0)
> code 0xff000020 found at 0xc (12), 12 bytes from previous
> code 0xff000020 found at 0x5b0 (1456), 1444 bytes from previous
> code 0xff000020 found at 0xb54 (2900), 1444 bytes from previous
> code 0xff000020 found at 0x10f8 (4344), 1444 bytes from previous
> code 0xff000020 found at 0x169c (5788), 1444 bytes from previous
> code 0xff000020 found at 0x1c40 (7232), 1444 bytes from previous
> code 0xff000020 found at 0x21e4 (8676), 1444 bytes from previous
> code 0xff000020 found at 0x2788 (10120), 1444 bytes from previous
> code 0xff000020 found at 0x2d2c (11564), 1444 bytes from previous
> code 0xff000020 found at 0x32d0 (13008), 1444 bytes from previous
> code 0xff000020 found at 0x3874 (14452), 1444 bytes from previous
> code 0xff000020 found at 0x3e18 (15896), 1444 bytes from previous
> code 0xff000020 found at 0x43bc (17340), 1444 bytes from previous
> code 0xff000060 found at 0x4960 (18784), 1444 bytes from previous
> code 0xff000060 found at 0x4f04 (20228), 1444 bytes from previous
> code 0xff000060 found at 0x54a8 (21672), 1444 bytes from previous
> code 0xff000060 found at 0x5a4c (23116), 1444 bytes from previous
> code 0xff000060 found at 0x5ff0 (24560), 1444 bytes from previous
> code 0xff000060 found at 0x6594 (26004), 1444 bytes from previous
> code 0xff000060 found at 0x6b38 (27448), 1444 bytes from previous
> code 0xff000060 found at 0x70dc (28892), 1444 bytes from previous
> code 0xff000060 found at 0x7680 (30336), 1444 bytes from previous
> code 0xff000060 found at 0x7c24 (31780), 1444 bytes from previous
> code 0xff000060 found at 0x81c8 (33224), 1444 bytes from previous
> code 0xff000060 found at 0x876c (34668), 1444 bytes from previous
> code 0xff000060 found at 0x8d10 (36112), 1444 bytes from previous
> code 0x3fffffff found at 0x92a8 (37544)
> code 0xff000020 found at 0x92b4 (37556), 1444 bytes from previous
> code 0xff000020 found at 0x9858 (39000), 1444 bytes from previous
> code 0xff000020 found at 0x9dfc (40444), 1444 bytes from previous
> code 0xff000020 found at 0xa3a0 (41888), 1444 bytes from previous
> code 0xff000020 found at 0xa944 (43332), 1444 bytes from previous
> code 0xff000020 found at 0xaee8 (44776), 1444 bytes from previous
> code 0xff000020 found at 0xb48c (46220), 1444 bytes from previous
> code 0xff000020 found at 0xba30 (47664), 1444 bytes from previous
> code 0xff000020 found at 0xbfd4 (49108), 1444 bytes from previous
> code 0xff000020 found at 0xc578 (50552), 1444 bytes from previous
> code 0xff000020 found at 0xcb1c (51996), 1444 bytes from previous
> code 0xff000020 found at 0xd0c0 (53440), 1444 bytes from previous
> code 0xff000020 found at 0xd664 (54884), 1444 bytes from previous
> code 0xff000060 found at 0xdc08 (56328), 1444 bytes from previous
> code 0xff000060 found at 0xe1ac (57772), 1444 bytes from previous
> code 0xff000060 found at 0xe750 (59216), 1444 bytes from previous
> code 0xff000060 found at 0xecf4 (60660), 1444 bytes from previous
> code 0xff000060 found at 0xf298 (62104), 1444 bytes from previous
> code 0xff000060 found at 0xf83c (63548), 1444 bytes from previous
> code 0xff000060 found at 0xfde0 (64992), 1444 bytes from previous
> code 0xff000060 found at 0x10384 (66436), 1444 bytes from previous
> code 0xff000060 found at 0x10928 (67880), 1444 bytes from previous
> code 0xff000060 found at 0x10ecc (69324), 1444 bytes from previous
> code 0xff000060 found at 0x11470 (70768), 1444 bytes from previous
> code 0xff000060 found at 0x11a14 (72212), 1444 bytes from previous
> code 0xff000060 found at 0x11fb8 (73656), 1444 bytes from previous
> code 0x3fffffff found at 0x12550 (75088)
> code 0xff000020 found at 0x1255c (75100), 1444 bytes from previous
> code 0xff000020 found at 0x12b00 (76544), 1444 bytes from previous
> code 0xff000020 found at 0x130a4 (77988), 1444 bytes from previous
> code 0xff000020 found at 0x13648 (79432), 1444 bytes from previous
> code 0xff000020 found at 0x13bec (80876), 1444 bytes from previous
> code 0xff000020 found at 0x14190 (82320), 1444 bytes from previous
> code 0xff000020 found at 0x14734 (83764), 1444 bytes from previous
> code 0xff000020 found at 0x14cd8 (85208), 1444 bytes from previous
> code 0xff000020 found at 0x1527c (86652), 1444 bytes from previous
> code 0xff000020 found at 0x15820 (88096), 1444 bytes from previous
> code 0xff000020 found at 0x15dc4 (89540), 1444 bytes from previous
> code 0xff000020 found at 0x16368 (90984), 1444 bytes from previous
> code 0xff000020 found at 0x1690c (92428), 1444 bytes from previous
> code 0xff000060 found at 0x16eb0 (93872), 1444 bytes from previous
> code 0xff000060 found at 0x17454 (95316), 1444 bytes from previous
> code 0xff000060 found at 0x179f8 (96760), 1444 bytes from previous
> code 0xff000060 found at 0x17f9c (98204), 1444 bytes from previous
> code 0xff000060 found at 0x18540 (99648), 1444 bytes from previous
> code 0xff000060 found at 0x18ae4 (101092), 1444 bytes from previous
> code 0xff000060 found at 0x19088 (102536), 1444 bytes from previous
> code 0xff000060 found at 0x1962c (103980), 1444 bytes from previous
> code 0xff000060 found at 0x19bd0 (105424), 1444 bytes from previous
> code 0xff000060 found at 0x1a174 (106868), 1444 bytes from previous
> code 0xff000060 found at 0x1a718 (108312), 1444 bytes from previous
> code 0xff000060 found at 0x1acbc (109756), 1444 bytes from previous
> code 0xff000060 found at 0x1b260 (111200), 1444 bytes from previous
> code 0x3fffffff found at 0x1b7f8 (112632)
> code 0xff000020 found at 0x1b804 (112644), 1444 bytes from previous
> code 0xff000020 found at 0x1bda8 (114088), 1444 bytes from previous
> code 0xff000020 found at 0x1c34c (115532), 1444 bytes from previous
> code 0xff000020 found at 0x1c8f0 (116976), 1444 bytes from previous
> code 0xff000020 found at 0x1ce94 (118420), 1444 bytes from previous
> code 0xff000020 found at 0x1d438 (119864), 1444 bytes from previous
> code 0xff000020 found at 0x1d9dc (121308), 1444 bytes from previous
> code 0xff000020 found at 0x1df80 (122752), 1444 bytes from previous
> code 0xff000020 found at 0x1e524 (124196), 1444 bytes from previous
> code 0xff000020 found at 0x1eac8 (125640), 1444 bytes from previous
> code 0xff000020 found at 0x1f06c (127084), 1444 bytes from previous
> code 0xff000020 found at 0x1f610 (128528), 1444 bytes from previous
> code 0xff000020 found at 0x1fbb4 (129972), 1444 bytes from previous
> code 0xff000060 found at 0x20158 (131416), 1444 bytes from previous
> code 0xff000060 found at 0x206fc (132860), 1444 bytes from previous
> code 0xff000060 found at 0x20ca0 (134304), 1444 bytes from previous
> code 0xff000060 found at 0x21244 (135748), 1444 bytes from previous
> code 0xff000060 found at 0x217e8 (137192), 1444 bytes from previous
> code 0xff000060 found at 0x21d8c (138636), 1444 bytes from previous
> code 0xff000060 found at 0x22330 (140080), 1444 bytes from previous
> code 0xff000060 found at 0x228d4 (141524), 1444 bytes from previous
> code 0xff000060 found at 0x22e78 (142968), 1444 bytes from previous
> code 0xff000060 found at 0x2341c (144412), 1444 bytes from previous
> code 0xff000060 found at 0x239c0 (145856), 1444 bytes from previous
> code 0xff000060 found at 0x23f64 (147300), 1444 bytes from previous
>
> So the '3fffffff' VBI frame header can be found at n*26*1444 but the
> last 12 samples of the last line of every frame are discarded by the
> encoder (no big deal).
>
> The 12 byte frame headers and the following SAV code from the data
> file are:
>
> 0000000: 3fffffff 00000000 00001515 ff000020
> 00092a8: 3fffffff 00000000 000020d1 ff000020
> 0012550: 3fffffff 00000000 00002c89 ff000020
> 001b7f8: 3fffffff 00000000 00003845 ff000020
>
> The differences between the changing numbers is 3004, 3000, & 3004
> decimal. If you consider those ticks of a 90 kHz clock like many
> MPEG timestamps, than those numbers are 33.38 ms, 33.33 ms, and 33.38
> ms or frame rates of 29.96 Hz, 30.0 Hz and 29.96 Hz. So it looks
> like the raw VBI stream from the encoder comes with time stamps.
>
>
> Now, if I could only get it not to stall....
You're now at the same place were I gave up at the time. I didn't spent
any effort on investigating this further since back then there were
much more important problems.
Don't hesitate to ask Sri and Steve questions (although I would contact
them in separate emails, I think).
Regards,
Hans
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